<title>「NOIP2012」同余方程</title><link href="http://hzoi.com/tomorrow.css" rel="stylesheet"><div class="ui existing segment"><pre><code><span class="pl-cp">#include</span> <span class="pl-cpf">&lt;cstdio&gt;</span><span class="pl-cp"></span>
<span class="pl-kt">int</span> <span class="pl-n">a</span><span class="pl-p">,</span> <span class="pl-n">b</span><span class="pl-p">,</span> <span class="pl-n">x</span><span class="pl-p">,</span> <span class="pl-n">y</span><span class="pl-p">,</span> <span class="pl-n">k</span><span class="pl-p">;</span>
<span class="pl-kt">void</span> <span class="pl-nf">exgcd</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">a</span><span class="pl-p">,</span> <span class="pl-kt">int</span> <span class="pl-n">b</span><span class="pl-p">)</span> <span class="pl-p">{</span>
    <span class="pl-k">if</span> <span class="pl-p">(</span><span class="pl-n">b</span> <span class="pl-o">==</span> <span class="pl-mi">0</span><span class="pl-p">)</span> <span class="pl-k">return</span> <span class="pl-n">x</span> <span class="pl-o">=</span> <span class="pl-mi">1</span><span class="pl-p">,</span> <span class="pl-n">y</span> <span class="pl-o">=</span> <span class="pl-mi">0</span><span class="pl-p">,</span> <span class="pl-kt">void</span><span class="pl-p">();</span>
    <span class="pl-n">exgcd</span><span class="pl-p">(</span><span class="pl-n">b</span><span class="pl-p">,</span> <span class="pl-n">a</span> <span class="pl-o">%</span> <span class="pl-n">b</span><span class="pl-p">),</span> <span class="pl-n">k</span> <span class="pl-o">=</span> <span class="pl-n">x</span><span class="pl-p">,</span> <span class="pl-n">x</span> <span class="pl-o">=</span> <span class="pl-n">y</span><span class="pl-p">,</span> <span class="pl-n">y</span> <span class="pl-o">=</span> <span class="pl-n">k</span> <span class="pl-o">-</span> <span class="pl-n">a</span> <span class="pl-o">/</span> <span class="pl-n">b</span> <span class="pl-o">*</span> <span class="pl-n">y</span><span class="pl-p">;</span>
<span class="pl-p">}</span>
<span class="pl-kt">int</span> <span class="pl-nf">main</span><span class="pl-p">()</span> <span class="pl-p">{</span>
    <span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d%d&quot;</span><span class="pl-p">,</span> <span class="pl-o">&amp;</span><span class="pl-n">a</span><span class="pl-p">,</span> <span class="pl-o">&amp;</span><span class="pl-n">b</span><span class="pl-p">);</span>
    <span class="pl-n">exgcd</span><span class="pl-p">(</span><span class="pl-n">a</span><span class="pl-p">,</span> <span class="pl-n">b</span><span class="pl-p">);</span>
    <span class="pl-n">printf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d&quot;</span><span class="pl-p">,</span> <span class="pl-p">(</span><span class="pl-n">x</span> <span class="pl-o">+</span> <span class="pl-n">b</span><span class="pl-p">)</span> <span class="pl-o">%</span> <span class="pl-n">b</span><span class="pl-p">);</span>
    <span class="pl-k">return</span> <span class="pl-mi">0</span><span class="pl-p">;</span>
<span class="pl-p">}</span>
</cpde></pre></div>